Adhesive film for metal terminal, method for producing adhesive film for metal terminal, metal terminal with adhesive film for metal terminal attached thereto, power storage device using said adhesive film for metal terminal, and method for producing power storage device

ABSTRACT

An adhesive film for a metal terminal is interposed between a metal terminal electrically connected to an electrode of a power storage device element, and a power storage device exterior material that seals the power storage device element, the adhesive film comprising a laminated body including, in the following order: a first polyolefin layer disposed on the metal terminal side; a base material; and a second polyolefin layer disposed on the power storage device exterior material side, wherein the adhesive film has a Martens hardness of at most 30 N/mm 2  as measured in a direction perpendicular to a cross-section in the thickness direction of the first polyolefin layer.

TECHNICAL FIELD

The present disclosure relates to an adhesive film for metal terminal, amethod for manufacturing an adhesive film for metal terminal, a metalterminal with an adhesive film for metal terminal, an electrical storagedevice using an adhesive film for metal terminal, and a method formanufacturing an electrical storage device.

BACKGROUND ART

Various types of electrical storage devices have been developedheretofore, and in every electrical storage device, an exterior materialfor electrical storage devices is an essential member for sealingelectrical storage device elements such as an electrode and anelectrolyte. Metallic exterior materials for electrical storage deviceshave been often used heretofore as exterior materials for electricalstorage devices, and in recent years, electrical storage devices havebeen required to be diversified in shape, and desired to be thinner andlighter as performance of, for example, electric cars, hybrid electriccars, personal computers, cameras and mobile phones has been enhanced.

However, metallic exterior materials for electrical storage devices thathave often been heretofore used have the disadvantage that it isdifficult to keep up with diversification in shape, and there is a limiton weight reduction.

Thus, in recent years, a laminated sheet with a base material layer, anadhesive layer, a barrier layer and a heat-sealable resin layerlaminated in this order has been proposed as an exterior material forelectrical storage devices which is easily processed into diversifiedshapes and is capable of achieving thickness reduction and weightreduction. When such a film-shaped exterior material for electricalstorage devices is used, a battery element is sealed with the packagingmaterial by heat-welding the peripheral edge of the exterior materialfor electrical storage devices by heat sealing while the heat-sealableresin layers located at the innermost layer of the exterior material forelectrical storage devices face each other.

A metal terminal protrudes from the heat-sealed portion of the exteriormaterial for electrical storage devices, and the electrical storagedevice element sealed by the exterior material for electrical storagedevices is electrically connected to the outside by a metal terminalelectrically connected to an electrode of the electrical storage deviceelement. That is, of the portion where the exterior material forelectrical storage devices is heat-sealed, a portion where the metalterminal is present is heat-sealed with the metal terminal is sandwichedbetween heat-sealable resin layers. Since the metal terminal and theheat-sealable resin layer are composed of different materials, adhesionis likely to decrease at an interface between the metal terminal and theheat-sealable resin layer.

Thus, an adhesive film may be disposed between the metal terminal andthe heat-sealable resin layer for the purpose of, for example, improvingadhesion between the metal terminal and the heat-sealable resin layer.Examples of the adhesive film include those described in Patent Document1.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Patent Laid-open Publication No. 2015-79638

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

As described above, an adhesive film disposed between a heat-sealableresin layer of an exterior material for electrical storage devices and ametal terminal is required to exhibit adhesion to the heat-sealableresin layer and the metal terminal when heat-sealed.

Further, if a gap is formed between the adhesive film and the metalterminal, there arises a problem that an electrolytic solution as thecontent of an electrical storage device flows out to the outside of theelectrical storage device. Therefore, the adhesive film is also requiredto have excellent followability which ensures that when heat-sealed tothe metal terminal, the adhesive film follows the shape of the metalterminal, so that a gap is not formed between the adhesive film and themetal terminal.

However, conventional adhesive films are not necessarily sufficient forachieving both adhesion and followability as mentioned above, and theinventors of the present disclosure have pursued further improvement ofadhesion and followability.

Under these circumstances, a main object of the present disclosure is toprovide an adhesive film for metal terminal which has excellent adhesionand excellent followability to a metal terminal. Further, an object ofthe present disclosure relates to a method for manufacturing theadhesive film for metal terminal, a metal terminal with an adhesive filmfor metal terminal using the adhesive film for metal terminal, anelectrical storage device using the adhesive film for metal terminal,and a method for manufacturing the electrical storage device.

Means for Solving the Problem

The inventors of the present disclosure have extensively conductedstudies for solving the above-described problems. As a result, theinventors have found that an adhesive film for metal terminal includinga laminated body including, in the following order: a first polyolefinlayer disposed on the metal terminal side; a base material; and a secondpolyolefin layer disposed on the side of an exterior material forelectrical storage devices, in which a martens hardness measured in aperpendicular direction with respect to a thickness-directioncross-section of the first polyolefin layer is set to be equal to orless than a predetermined value under predetermined measurementconditions, exhibits excellent adhesion and followability to the metalterminal when heat-sealed to the metal terminal. The present disclosureis an invention that has been completed by further conducting studiesbased on the above-mentioned findings.

That is, the present disclosure provides an invention of an aspect asdescribed below:

an adhesive film for metal terminal, which is interposed between a metalterminal electrically connected to an electrode of an electrical storagedevice element and an exterior material for electrical storage devicesthat seals the electrical storage device element,

in which the adhesive film for metal terminal includes a laminated bodyincluding, in the following order: a first polyolefin layer disposed onthe metal terminal side: a base material; and a second polyolefin layerdisposed on the side of the exterior material for electrical storagedevices, and

a martens hardness measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer is 30N/mm² or less under the following conditions.

<Martens hardness measurement conditions>

A load of 10 mN. The load is either a test load as well as a maximumload.

A load application speed of 1 mN/10 seconds.

A retention time of 10 seconds.

A load releasing speed of 1 mN/10 seconds.

Indenter: Vickers indenter in which the facing angle of a regularquadrangular pyramid-shaped tip end portion is 136°.

A measurement temperature of 25° C.

Measured value: an average of a total of eight measured values obtainedby measuring ten times with the measurement location changed each time,and then excluding one maximum value and one minimum value.

Advantages of the Invention

According to the present disclosure, it is possible to provide anadhesive film for metal terminal which has excellent adhesion andexcellent followability to a metal terminal. Further, an object of thepresent disclosure relates to a method for manufacturing the adhesivefilm for metal terminal, a metal terminal with an adhesive film formetal terminal using the adhesive film for metal terminal, an electricalstorage device using the adhesive film for metal terminal, and a methodfor manufacturing the electrical storage device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of an electrical storage device of thepresent disclosure.

FIG. 2 is a schematic sectional view taken along line A-A′ in FIG. 1 .

FIG. 3 is a schematic sectional view taken along line B-B′ in FIG. 1 .

FIG. 4 is a schematic sectional view of an adhesive film for metalterminal of the present disclosure.

FIG. 5 is a schematic sectional view of an adhesive film for metalterminal according to the present disclosure.

FIG. 6 is a schematic sectional view of an exterior material forelectrical storage devices for electrical storage devices according tothe present disclosure.

FIG. 7 is a schematic sectional view of a laminated body of adhesivefilm/metal terminal/adhesive film (a metal terminal with an adhesivefilm for metal terminal) obtained by sandwiching a metal terminalbetween two adhesive films and heat-welding the adhesive films in anexample.

FIG. 8 is an image diagram of a graph showing a relationship between adepth of indentation (μm) and a load (mN) which is obtained by measuringa martens hardness, an indentation elastic modulus, and a depth ofindentation h_(max).

FIG. 9 is a schematic diagram for illustrating a method for measuring amartens hardness by pressing an indenter in a perpendicular direction toa thickness-direction cross-section of a first polyolefin layer of anadhesive film for metal terminal.

EMBODIMENTS OF THE INVENTION

The adhesive film for metal terminal according to the present disclosureis an adhesive film for metal terminal which is interposed between ametal terminal electrically connected to an electrode of an electricalstorage device element and an exterior material for electrical storagedevices that seals the electrical storage device element, in which theadhesive film for metal terminal includes a laminated body including, inthe following order: a first polyolefin layer disposed on the metalterminal side; a base material; and a second polyolefin layer disposedon the side of the exterior material for electrical storage devices, and

a martens hardness measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer is 30N/mm² or less under the following conditions.

<Martens hardness measurement conditions>

A load of 10 mN.

A load application speed of 1 mN/10 seconds.

A retention time of 10 seconds.

A load releasing speed of 1 mN/10 seconds.

Indenter: Vickers indenter in which the facing angle of a regularquadrangular pyramid-shaped tip end portion is 136°.

A measurement temperature of 25° C.

Measured value: an average of a total of eight measured values obtainedby measuring ten times with the measurement location changed each time,and then excluding one maximum value and one minimum value.

To a cross-section of the first polyolefin layer of the adhesive filmfor metal terminal in a thickness direction Y (i.e. a cross-sectionobtained by cutting the adhesive film for metal terminal in a thicknessdirection), an indenter is pressed in a direction x perpendicular to thethickness direction y (arrow in FIG. 9 ) to measure the martens hardnessas shown in the schematic diagram of FIG. 9 .

The adhesive film for metal terminal according to the present disclosureexhibits excellent adhesion and excellent followability to the metalterminal when heat-sealed because the martens hardness of the firstpolyolefin layer disposed on the metal terminal side is set to 30 N/mm²or less.

The electrical storage device of the present disclosure is an electricalstorage device including: an electrical storage device element includingat least a positive electrode, a negative electrode and an electrolyte;an exterior material for electrical storage devices that seals theelectrical storage device element; and a metal terminal electricallyconnected to each of the positive electrode and the negative electrodeand protruding to the outside of the exterior material for electricalstorage devices, in which the adhesive film for metal terminal accordingto the present disclosure is interposed between the metal terminal andthe exterior material for electrical storage devices. Hereinafter, theadhesive film for metal terminal, the method for manufacturing theadhesive film for metal terminal, the electrical storage device usingthe adhesive film for metal terminal, and the method for manufacturingthe electrical storage device according to the present disclosure willbe described in detail.

For the numerical range in this specification, a numerical rangeindicated by the term “A to B” means “A or more” and “B or less”. Forexample, the expression of “2 to 15 mm” means 2 mm or more and 15 mm orless.

In addition, examples of the method for identifying MD of the adhesivefilm for metal terminal in which a cross-section of the adhesive filmfor metal terminal (e.g. a cross-section of the first polyolefin layer,the base material or the second polyolefin layer) is observed with anelectron microscope to identify a sea-island structure. In the method,the direction parallel to a cross-section in which the average of thediameters of the island shapes in a direction perpendicular to thethickness direction of the adhesive film for metal terminal is maximumcan be determined as MD. Specifically, a length-direction cross-sectionof the adhesive film for metal terminal and cross-sections (a total of10 cross-sections) at angular intervals of 10 degrees from a directionparallel to the length-direction cross-section to a directionperpendicular to the length-direction cross-section are observed with anelectron microscope photograph to examine sea-island structures. Next,in each cross-section, the shape of each island is observed. For theshape of each island, the linear distance between the leftmost end in adirection perpendicular to the thickness direction of the adhesive filmfor metal terminal and the rightmost end in the perpendicular directionis defined as a diameter y. In each cross-section, the average of thetop 20 diameters y in descending order of the diameter y of the islandshape is calculated. The direction parallel to a cross-section havingthe largest average of the diameters y of the island shapes isdetermined as MD.

1. Adhesive film for metal terminal

The adhesive film for metal terminal according to the present disclosureis interposed between a metal terminal electrically connected to anelectrode of an electrical storage device element and an exteriormaterial for electrical storage devices for sealing the electricalstorage device element. Specifically, as shown in, for example, FIGS. 1to 3 , an adhesive film 1 for metal terminal according to the presentdisclosure is interposed between a metal terminal 2 electricallyconnected to an electrode of an electrical storage device element 4 andan exterior material 3 for electrical storage devices for sealing theelectrical storage device element 4. The metal terminal 2 protrudes tothe outside of the exterior material 3 for electrical storage devices,and is sandwiched between the exterior materials 3 for electricalstorage devices with the adhesive film 1 for metal terminal interposedbetween the metal terminal 2 and the exterior material 3 at a peripheraledge portion 3 a of the heat-sealed exterior material 3 for electricalstorage devices. In the present disclosure, the heating temperature istypically in the range of about 160 to 190° C. and the pressure istypically in the range of about 1.0 to 2.0 MPa at the time ofheat-sealing the exterior material for electrical storage devices. Inthe step of bonding the metal terminal to the exterior material forelectrical storage devices with the adhesive film interposedtherebetween, heating and pressurization are performed multiple times,for example, the steps of temporary bonding and primary bonding to themetal terminal are carried out. The temporary bonding step is a step oftemporarily fixing the adhesive film to the metal terminal and removingair bubbles, and the primary bonding step is a step of bonding theadhesive film to the metal terminal by performing heating andpressurizing one or more times under the condition of a highertemperature over the temporary bonding step. The step of temporarilybonding the adhesive film for metal terminal to a metal terminal isperformed under the conditions of a temperature of, for example, about140 to 160° C., a pressure of about 0.01 to 1.0 MPa, a time of about 3to 15 seconds, and about 3 to 6 times, and the primary bonding step isperformed under the conditions of, for example, a temperature of about160 to 240° C., a pressure of about 0.01 to 1.0 MPa, a time of about 3to 15 seconds, and about 1 to 3 times.

The adhesive film 1 for metal terminal according to the presentdisclosure is provided for enhancing adhesion between the metal terminal2 and the exterior material 3 for electrical storage devices.Enhancement of adhesion between the metal terminal 2 and exteriormaterial 3 for electrical storage devices improves the sealing propertyof the electrical storage device element 4. As described above, theelectrical storage device element is sealed such that the metal terminal2 electrically connected to the electrode of the electrical storagedevice element 4 protrudes to the outside of the exterior material 3 forelectrical storage devices when the electrical storage device element 4is heat-sealed. Here, the metal terminal 2 formed of metal and aheat-sealable resin layer 35 (a layer formed of a heat-sealable resinsuch as a polyolefin) located in the innermost layer of the exteriormaterial 3 for electrical storage devices are formed of differentmaterials, and therefore when such an adhesive film is not used, thesealing property of the electrical storage device element is likely tobe low at the interface between the metal terminal 2 and theheat-sealable resin layer 35.

As shown in FIGS. 4 and 5 , the adhesive film 1 for metal terminalaccording to the present disclosure has a configuration in which atleast a first polyolefin layer 12 a, a base material 11 and a secondpolyolefin layer 12 b are laminated in this order. The first polyolefinlayer 12 a is disposed on the metal terminal side. In addition, thesecond polyolefin layer 12 b is disposed on the side of the exteriormaterial 3 for electrical storage devices. As shown in FIGS. 4 and 5 ,the first polyolefin layer 12 a and the second polyolefin layer 12 b arelocated, respectively, on surfaces on both sides in the adhesive film 1for metal terminal.

In the adhesive film 1 for metal terminal, the first polyolefin layer 12a and the second polyolefin layer 12 b each contain a polyolefin-basedresin. Examples of the polyolefin-based resin include polyolefins andacid-modified polyolefins. It is preferable that the first polyolefinlayer 12 a contains an acid-modified polyolefin, among polyolefin-basedresins, and it is more preferable that the first polyolefin layer 12 ais a layer formed of an acid-modified polyolefin. It is preferable thatthe second polyolefin layer 12 b contains a polyolefin or anacid-modified polyolefin, more preferably a polyolefin, amongpolyolefin-based resins, and it is still more preferable that the secondpolyolefin layer 12 b is a layer formed of a polyolefin. When the resinforming the second polyolefin layer 12 b disposed on the side of theexterior material 3 for electrical storage devices is identical to theresin forming the heat-sealable resin layer 35 of the exterior material3 for electrical storage devices, adhesion between the adhesive film 1for metal terminal according to the present disclosure and the exteriormaterial for electrical storage devices is enhanced.

It is preferable that the base material contains a polyolefin-basedresin, more preferably a polyolefin, and it is still more preferablethat the base material 11 is a layer formed of a polyolefin.

In each of the first polyolefin layer 12 a, the second polyolefin layer12 b and the base material 11, the polyolefin-based resin is preferablya polypropylene-based resin, the polyolefin is preferably polypropylene,and the acid-modified polyolefin is preferably acid-modifiedpolypropylene. The polyolefin-based resin such as a polyolefin and anacid-modified polyolefin may contain known additives, fillers describedlater, pigments, and the like.

Specific examples of the preferred laminated configuration of theadhesive film 1 for metal terminal according to the present disclosureinclude a three-layer configuration in which a first polyolefin layerformed of acid-modified polypropylene, a base material formed ofpolypropylene and a second polyolefin layer formed of polypropylene arelaminated in this order; and a three-layer configuration in which afirst polyolefin layer formed of acid-modified polypropylene, a basematerial formed of polypropylene and a second polyolefin layer formed ofacid-modified polypropylene are laminated in this order. Among them, athree-layer configuration is particularly preferable in which a firstpolyolefin layer formed of acid-modified polypropylene/a base materialformed of polypropylene/a second polyolefin layer formed ofpolypropylene are laminated in this order.

Materials forming the first polyolefin layer 12 a, the second polyolefinlayer 12 b and the base material 11 will be described later in detail.

When the adhesive film 1 for metal terminal according to the presentdisclosure is disposed between the metal terminal 2 of the electricalstorage device 10 and the exterior material 3 for electrical storagedevices, the surface of the metal terminal 2 composed of metal and theheat-sealable resin layer 35 (a layer formed of a heat-sealable resinsuch as a polyolefin) of the exterior material 3 for electrical storagedevices are bonded to each other with the adhesive film 1 for metalterminal interposed therebetween. The first polyolefin layer 12 a of theadhesive film 1 for metal terminal is disposed on the metal terminal 2side, the second polyolefin layer 12 b is disposed on the side of theexterior material 3 for electrical storage devices, the first polyolefinlayer 12 a adheres to the metal terminal 2, and the second polyolefinlayer 12 b adheres to the heat-sealable resin layer 35 of the exteriormaterial 3 for electrical storage devices.

In the adhesive film 1 for metal terminal according to the presentdisclosure, the martens hardness measured in a direction perpendicularto a thickness-direction cross-section of the first polyolefin layer 12a is 30 N/mm² or less. The adhesive film 1 for metal terminal accordingto the present disclosure can exhibit excellent adhesion andfollowability to the metal terminal 2 because the first polyolefin layer12 a disposed on the metal terminal 2 side has high flexibility. Withoutwishing to make a limited interpretation, it is considered thatexcellent adhesion and followability to the metal terminal 2 areexhibited because the first polyolefin layer 12 a is easily embedded ina gap between the metal terminal and the exterior material forelectrical storage devices due to high flexibility of the firstpolyolefin layer 12 a, and the first polyolefin layer 12 a easilyextends in the thickness direction of the metal terminal. The conditionsfor measurement of the martens hardness are as follows. As pretreatmentof a sample to be measured, the adhesive film for metal terminal is cutto 30 mm in MD and 15 mm in TD. Next, the sample is embedded in epoxycold implant resin and dried for about 1 day. Thereafter, using amechanical polishing apparatus Tegrapol-35 manufactured by MarumotoStruers K.K., a cross-section obtained by cutting in a transversedirection is polished to set the surface roughness of the cross-sectionof the sample to about 1.0 μm. The martens hardness is measured by anindentation method. The measurement by an indentation method can beperformed using, for example, PICODENTOR HM-500 manufactured by FISCHERINSTRUMENTS K.K.

<Martens hardness measurement conditions>

A load of 10 mN.

A load application speed of 1 mN/10 seconds.

A retention time of 10 seconds.

A load releasing speed of 1 mN/10 seconds.

Indenter: Vickers indenter in which the facing angle of a regularquadrangular pyramid-shaped tip end portion is 136°.

A measurement temperature of 25° C.

Measured value: an average of a total of eight measured values obtainedby measuring ten times with the measurement location changed each time,and then excluding one maximum value and one minimum value.

The martens hardness of the first polyolefin layer 12 a may be 30 N/mm²or less, and is preferably about 25 N/mm² or less, more preferably about20 N/mm² or less, still more preferably about 15 N/mm² or less,particularly preferably about 12 N/mm² or less, from the viewpoint ofmore suitably exhibiting excellent adhesion and excellent followabilityto the metal terminal 2. In addition, the martens hardness of the firstpolyolefin layer 12 a is preferably about 3 N/mm² or more, morepreferably about 5 N/mm² or more, still more preferably about 8 N/mm² ormore. The martens hardness of the first polyolefin layer 12 a ispreferably in the range of about 3 to 30 N/mm², about 3 to 25 N/mm²,about 3 to 20 N/mm², about 3 to 15 N/mm², about 3 to 12 N/mm², about 5to 30 N/mm², about 5 to 25 N/mm², about 5 to 20 N/mm², about 5 to 15N/mm², about 5 to 12 N/mm², about 8 to 30 N/mm², about 8 to 25 N/mm²,about 8 to 20 N/mm², about 8 to 15 N/mm², or about 8 to 12 N/mm².

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, theindentation elastic modulus measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer 12 aunder the martens hardness measurement conditions is preferably about400 MPa or less, more preferably about 350 MPa or less, still morepreferably about 300 MPa or less, even more preferably about 250 MPa orless, particularly preferably about 200 MPa or less. In addition, theindentation elastic modulus of the first polyolefin layer 12 a ispreferably about 100 MPa or more, more preferably about 120 MPa or more,still more preferably about 150 MPa or more. The indentation elasticmodulus of the first polyolefin layer 12 a is preferably in the range ofabout 100 to 400 MPa, about 100 to 350 MPa, about 100 to 300 MPa, about100 to 250 MPa, about 100 to 200 MPa, about 120 to 400 MPa, about 120 to350 MPa, about 120 to 300 MPa, about 120 to 250 MPa, about 120 to 200MPa, about 150 to 400 MPa, about 150 to 350 MPa, about 150 to 300 MPa,about 150 to 250 MPa, or about 150 to 200 MPa.

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, the depthof indentation h_(max) at a load of 10 mN, which is measured in adirection perpendicular to a thickness-direction cross-section of thefirst polyolefin layer 12 a under the martens hardness measurementconditions is preferably about 4.0 μm or more, more preferably about 4.5μm or more, still more preferably about 4.8 μm or more, even morepreferably about 5.0 μm or more, even more preferably about 5.5 μm ormore, particularly preferably about 6.0 μm or more. In addition, thedepth of indentation h_(max) of the first polyolefin layer 12 a ispreferably about 10.0 μm or less, more preferably about 8.0 μm or less,still more preferably about 7.0 μm or less. The depth of indentationh_(max) of the first polyolefin layer 12 a is preferably in the range ofabout 4.0 to 10.0 μm, about 4.0 to 8.0 μm, about 4.0 to 7.0 μm, about4.5 to 10.0 μm, about 4.5 to 8.0 μm, about 4.5 to 7.0 μm, about 4.8 to10.0 μm, about 4.8 to 8.0 μm, about 4.8 to 7.0 μm, about 5.0 to 10.0 μm,about 5.0 to 8.0 μm, about 5.0 to 7.0 μm, about 5.5 to 10.0 μm, about5.5 to 8.0 μm, or about 5.5 to 7.0 μm.

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, themartens hardness measured in a direction perpendicular to athickness-direction cross-section of the second polyolefin layer 12 bunder the martens hardness measurement conditions is preferably about 60N/mm² or less, more preferably about 50 N/mm² or less, still morepreferably about 45 N/mm² or less. In addition, the martens hardness ofthe second polyolefin layer 12 b is preferably about 8 N/mm² or more,more preferably about 15 N/mm² or more, still more preferably about 20N/mm² or more, even more preferably about 25 N/mm² or more, particularlypreferably about 30 N/mm² or more. The martens hardness of the secondpolyolefin layer 12 b is preferably in the range of about 8 to 60 N/mm²,about 8 to 50 N/mm², about 8 to 45 N/mm², about 15 to 60 N/mm², about 15to 50 N/mm², about 15 to 45 N/mm², about 20 to 60 N/mm², about 20 to 50N/mm², about 20 to 45 N/mm², about 25 to 60 N/mm², about 25 to 50 N/mm²,about 25 to 45 N/mm², about 30 to 60 N/mm², about 30 to 50 N/mm², orabout 30 to 45 N/mm².

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, theindentation elastic modulus measured in a direction perpendicular to athickness-direction cross-section of the second polyolefin layer 12 bunder the martens hardness measurement conditions is preferably about1500 MPa or less, more preferably about 1200 MPa or less, still morepreferably about 1000 MPa or less, even more preferably about 800 MPa orless. In addition, the indentation elastic modulus of the secondpolyolefin layer 12 b is preferably about 400 MPa or more, morepreferably about 500 MPa or more, still more preferably about 600 MPa ormore, even more preferably about 700 MPa or more. The indentationelastic modulus of the second polyolefin layer 12 b is preferably in therange of about 400 to 1500 MPa, about 400 to 1200 MPa, about 400 to 1000MPa, about 400 to 800 MPa, about 500 to 1500 MPa, about 500 to 1200 MPa,about 500 to 1000 MPa, about 500 to 800 MPa, about 600 to 1500 MPa,about 600 to 1200 MPa, about 600 to 1000 MPa, about 600 to 800 MPa,about 700 to 1500 MPa, about 700 to 1200 MPa, about 700 to 1000 MPa, orabout 700 to 800 MPa.

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, the depthof indentation h_(max) at a load of 10 mN, which is measured in adirection perpendicular to a thickness-direction cross-section of thesecond polyolefin layer 12 b under the martens hardness measurementconditions is preferably about 2.5 μm or more, more preferably about 2.8μm or more, still more preferably about 3.0 μm or more. In addition, thedepth of indentation h_(max) of the second polyolefin layer 12 b ispreferably about 5.0 μm or less, more preferably about 4.5 μm or less,still more preferably about 4.0 μm or less. The depth of indentationh_(max) of the second polyolefin layer 12 b is preferably in the rangeof about 2.5 to 5.0 μm, about 2.5 to 4.5 μm, about 2.5 to 4.0 μm, about2.8 to 5.0 μm, about 2.8 to 4.5 μm, about 2.8 to 4.0 μm, about 3.0 to5.0 μm, about 3.0 to 4.5 μm, or about 3.0 to 4.0 μm.

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, themartens hardness measured in a direction perpendicular to athickness-direction cross-section of the base material 11 under themartens hardness measurement conditions is preferably about 60 N/mm² orless, more preferably about 50 N/mm² or less, still more preferablyabout 45 N/mm² or less. In addition, the martens hardness of the basematerial 11 is preferably about 10 N/mm² or more, more preferably about15 N/mm² or more, still more preferably about 20 N/mm² or more, evenmore preferably about 25 N/mm² or more, particularly preferably about 30N/mm² or more. The martens hardness of the base material 11 ispreferably in the range of about 10 to 60 N/mm², about 10 to 50 N/mm²,about 10 to 45 N/mm², about 15 to 60 N/mm², about 15 to 50 N/mm², about15 to 45 N/mm², about 20 to 60 N/mm², about 20 to 50 N/mm², about 20 to45 N/mm², about 25 to 60 N/mm², about 25 to 50 N/mm², about 25 to 45N/mm², about 30 to 60 N/mm², about 30 to 50 N/mm², or about 30 to 45N/mm².

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, theindentation elastic modulus measured in a direction perpendicular to athickness-direction cross-section of the base material 11 under themartens hardness measurement conditions is preferably about 1500 MPa orless, more preferably about 1200 MPa or less, still more preferablyabout 1000 MPa or less, even more preferably about 800 MPa or less. Inaddition, the indentation elastic modulus of the base material 11 ispreferably about 200 MPa or more, more preferably about 300 MPa or more,still more preferably about 500 MPa or more, even more preferably about700 MPa or more. The indentation elastic modulus of the base material 11is preferably in the range of about 200 to 1500 MPa, about 200 to 1200MPa, about 200 to 1000 MPa, about 200 to 800 MPa, about 300 to 1500 MPa,about 300 to 1200 MPa, about 300 to 1000 MPa, about 300 to 800 MPa,about 500 to 1500 MPa, about 500 to 1200 MPa, about 500 to 1000 MPa,about 500 to 800 MPa, about 700 to 1500 MPa, about 700 to 1200 MPa,about 700 to 1000 MPa, or about 700 to 800 MPa.

In addition, from the viewpoint of more suitably exhibiting excellentadhesion and excellent followability to the metal terminal 2, the depthof indentation h_(max) at a load of 10 mN, which is measured in adirection perpendicular to a thickness-direction cross-section of thebase material 11 under the martens hardness measurement conditions ispreferably about 2.5 μm or more, more preferably about 2.8 μm or more,still more preferably about 3.0 μm or more. In addition, the depth ofindentation h_(max) of the base material 11 is preferably about 5.0 μmor less, more preferably about 4.5 μm or less, still more preferablyabout 4.0 μm or less. The depth of indentation h_(max) of the basematerial 11 is preferably in the range of about 2.5 to 5.0 μm, about 2.5to 4.5 μm, about 2.5 to 4.0 μm, about 2.8 to 5.0 μm, about 2.8 to 4.5μm, about 2.8 to 4.0 μm, about 3.0 to 5.0 μm, about 3.0 to 4.5 μm, orabout 3.0 to 4.0 μm.

In the adhesive film 1 for metal terminal according to the presentdisclosure, the martens hardness, the indentation elastic modulus andthe depth of indentation h_(max) of each of the first polyolefin layer12 a, the second polyolefin layer 12 b and the base material 11 can beadjusted by the composition, backbone, dispersibility, molecular weight,melting point and MFR of the resin forming each layer, and conditions(e.g. the extrusion width from the T-die, the draw ratio, the draw speedand the heat treatment temperature) of a T-die and inflation inmanufacturing of the adhesive film 1 for metal terminal. Examples of themethod for adjusting the martens hardness, the indentation elasticmodulus, and the depth of indentation h_(max) of the first polyolefinlayer of the adhesive film for metal terminal by the composition of thefirst polyolefin layer 12 a include a method in which a predeterminedamount of a butene component, an ethylene-propylene-butene copolymer, anoncrystalline ethylene-propylene copolymer, a propylene-α-olefincopolymer or the like is added for improving flexibility.

From the viewpoint of enhancing followability to the shape of the metalterminal 2, the total thickness of the adhesive film 1 for metalterminal according to the present disclosure is, for example, about 60μm or more, preferably about 80 μm or more, preferably about 100 μm ormore, more preferably about 120 μm or more, still more preferably about150 μm or more. In addition, the total thickness of the adhesive film 1for metal terminal according to the present disclosure is preferablyabout 200 μm or less, more preferably 180 μm or less. The totalthickness of the adhesive film 1 for metal terminal according to thepresent disclosure is preferably in the range of about 60 to 200 μm,about 60 to 180 μm, about 80 to 200 μm, about 80 to 180 μm, about 100 to200 μm, about 100 to 180 μm, about 120 to 200 μm, about 120 to 180 μm,about 150 to 200 μm, or about 150 to 180 μm. As a more specific example,for example, the total thickness is preferably about 60 to 100 μm whenthe adhesive film 1 for metal terminal according to the presentdisclosure is used for consumer electrical storage devices, and thetotal thickness is preferably about 100 to 200 μm when the adhesive film1 for metal terminal is used for vehicle-mounted power storage devices.

Hereinafter, the first polyolefin layer 12 a, the second polyolefinlayer 12 b and the base material 11 will be described in detail.

[First Polyolefin Layer 12 a and Second Polyolefin Layer 12 b]

As shown in FIGS. 4 and 5 , the adhesive film 1 for metal terminalaccording to the present disclosure includes the first polyolefin layer12 a on one side of the base material 11 and the second polyolefin layer12 b on the other side of the base material 11. The first polyolefinlayer 12 a is disposed on the metal terminal 2 side. In addition, thesecond polyolefin layer 12 b is disposed on the side of the exteriormaterial 3 for electrical storage devices. As shown in FIGS. 4 and 5 ,the first polyolefin layer 12 a and the second polyolefin layer 12 b arelocated, respectively, on surfaces on both sides in the adhesive film 1for metal terminal.

In the adhesive film 1 for metal terminal, the first polyolefin layer 12a and the second polyolefin layer 12 b each contain a polyolefin-basedresin. Examples of the polyolefin-based resin include polyolefins andacid-modified polyolefins. It is preferable that the first polyolefinlayer 12 a contains an acid-modified polyolefin, among polyolefin-basedresins, and it is more preferable that the first polyolefin layer 12 ais a layer formed of an acid-modified polyolefin. It is preferable thatthe second polyolefin layer 12 b contains a polyolefin or anacid-modified polyolefin, more preferably a polyolefin, amongpolyolefin-based resins, and it is still more preferable that the secondpolyolefin layer 12 b is a layer formed of a polyolefin. Theacid-modified polyolefin has high affinity for a metal. In addition, thepolyolefin has high affinity for a heat-weldable resin such as apolyolefin. Therefore, in the adhesive film 1 for metal terminalaccording to the present disclosure, further excellent adhesion can beexhibited at an interface between the adhesive film 1 for metal terminaland the metal terminal 2 by disposing the first polyolefin layer 12 aformed of an acid-modified polyolefin on the metal terminal 2 side. Inaddition, further excellent adhesion can be exhibited at an interfacebetween the adhesive film 1 for metal terminal and the heat-sealableresin layer 35 by disposing the second polyolefin layer 12 b formed of apolyolefin on the heat-sealable resin layer 35 side of the exteriormaterial 3 for electrical storage devices.

Specific examples of the preferred laminated configuration of theadhesive film 1 for metal terminal according to the present disclosureinclude a three-layer configuration in which a first polyolefin layerformed of acid-modified polypropylene, a base material formed ofpolypropylene and a second polyolefin layer formed of polypropylene arelaminated in this order; and a three-layer configuration in which afirst polyolefin layer formed of acid-modified polypropylene, a basematerial formed of polypropylene and a second polyolefin layer formed ofacid-modified polypropylene are laminated in this order. Among them, athree-layer configuration is particularly preferable in which a firstpolyolefin layer formed of acid-modified polypropylene/a base materialformed of polypropylene/a second polyolefin layer formed ofpolypropylene are laminated in this order.

The acid-modified polyolefin is not particularly limited as long as itis a polyolefin modified with an acid, and a polyolefin graft-modifiedwith an unsaturated carboxylic acid or an anhydride thereof ispreferable.

Specific examples of the polyolefin to be acid-modified includepolyethylenes such as low-density polyethylene, medium-densitypolyethylene, high-density polyethylene and linear low-densitypolyethylene; crystalline or noncrystalline polypropylene such ashomopolypropylene, block copolymers of polypropylene (e.g., blockcopolymers of propylene and ethylene) and random copolymers ofpolypropylene (e.g., random copolymers of propylene and ethylene);terpolymers of ethylene-butene-propylene; and the like. Among thesepolyolefins, polyethylenes and polypropylene are preferable, withpolypropylene being particularly preferable.

The polyolefin modified with an acid may be a cyclic polyolefin. Forexample, the carboxylic acid-modified cyclic polyolefin is a polymerobtained by performing copolymerization with an α,β-unsaturatedcarboxylic acid or an anhydride thereof replacing a part of monomersthat form the cyclic polyolefin, or by block-polymerizing orgraft-polymerizing an α,β-unsaturated carboxylic acid or an anhydridethereof with the cyclic polyolefin.

The cyclic polyolefin modified with an acid is a copolymer of an olefinand a cyclic monomer, and examples of the olefin as a constituentmonomer of the cyclic polyolefin include ethylene, propylene,4-methyl-1-pentene, butadiene and isoprene. Examples of the cyclicmonomer as a constituent monomer of the cyclic polyolefin include cyclicalkenes such as norbornene, specifically cyclic dienes such ascyclopentadiene, dicyclopentadiene, cyclohexadiene and norbornadiene.Among these polyolefins, cyclic alkenes are preferable, and norborneneis further preferable. Examples of the constituent monomer includestyrene.

Examples of the carboxylic acid or anhydride thereof which is used foracid modification include maleic acid, acrylic acid, itaconic acid,crotonic acid, maleic anhydride and itaconic anhydride. It is preferablethat a peak derived from maleic anhydride is detected when the firstpolyolefin layer 12 a is analyzed by infrared spectroscopy. For example,when a maleic anhydride-modified polyolefin is measured by infraredspectroscopy, peaks derived from maleic anhydride are detected nearwavenumbers of 1760 cm⁻¹ and 1780 cm⁻¹. When the first polyolefin layer12 a or the second polyolefin layer 12 b is a layer formed of a maleicanhydride-modified polyolefin, a peak derived from maleic anhydride isdetected when measurement is performed by infrared spectroscopy.However, if the degree of acid modification is low, the peaks may be toosmall to be detected. In that case, the peaks can be analyzed by nuclearmagnetic resonance spectroscopy.

The first polyolefin layer 12 a and the second polyolefin layer 12 b maybe each formed from one resin component alone, or may be formed from ablend polymer obtained by combining two or more resin components.Further, the first polyolefin layer 12 a and the second polyolefin layer12 b may be each formed of only one layer, but may be formed of two ormore layers with the same resin component or different resin components.From formability of the first polyolefin layer 12 a and the secondpolyolefin layer 12 b, it is preferable that these layers are eachformed from a blend polymer obtained by combining two or more resincomponents. When formed from the blend polymer, it is preferable thatthe first polyolefin layer 12 a contains acid-modified polypropylene asa main component (component contained at 50 mass % or more), and otherresins at 50 mass % or less (polyethylene is preferable from theviewpoint of improving flexibility). In addition, it is preferable thatthe second polyolefin layer 12 b contains polypropylene as a maincomponent (component contained at 50 mass % or more), and other resinsat 50 mass % or less (polyethylene is preferable from the viewpoint ofimproving flexibility). On the other hand, from the viewpoint of theelectrolytic solution resistance of the first polyolefin layer 12 a andthe second polyolefin layer 12 b, it is preferable that the firstpolyolefin layer 12 a contains acid-modified polypropylene alone as aresin, and it is preferable that the second polyolefin layer 12 bcontains polypropylene alone as a resin.

Further, the first polyolefin layer 12 a and the second polyolefin layer12 b may each contain a filler if necessary. When the first polyolefinlayer 12 a and the second polyolefin layer 12 b contain a filler, ashort circuit between the metal terminal 2 and a barrier layer 33 of theexterior material 3 for electrical storage devices can be effectivelysuppressed because the filler functions as a spacer. The particle sizeof the filler is in the range of about 0.1 to 35 μm, preferably about5.0 to 30 μm, more preferably about 10 to 25 μm. In addition, thecontents of the fillers based on 100 parts by mass of resin componentsforming the first polyolefin layer 12 a and the second polyolefin layer12 b, respectively, are each about 5 to 30 parts by mass, morepreferably about 10 to 20 parts by mass.

As the filler, either an inorganic filler or an organic filler can beused. Examples of the inorganic filler include carbon (carbon,graphite), silica, aluminum oxide, barium titanate, iron oxide, siliconcarbide, zirconium oxide, zirconium silicate, magnesium oxide, titaniumoxide, calcium aluminate, calcium hydroxide, aluminum hydroxide,magnesium hydroxide and calcium carbonate. In addition, examples of theorganic filler include fluororesins, phenol resins, urea resins, epoxyresins, acrylic resins, benzoguanamine-formaldehyde condensates,melamine-formaldehyde condensates, crosslinked products of polymethylmethacrylate, and crosslinked products of polyethylene. From theviewpoint of shape stability, rigidity and content resistance, aluminumoxide, silica, fluororesins, acrylic resins andbenzoguanamine-formaldehyde condensates are preferable, and among them,spherical aluminum oxide and silica are more preferable. As a method formixing the filler with resin components that form the first polyolefinlayer 12 a and the second polyolefin layer 12 b, a method in which amasterbatch formed by melting and blending the resin components and thefiller with a Banbury mixer or the like is adjusted to a predeterminedmixing ratio; a method in which the filler is directly mixed with theresin components; or the like can be adopted.

In addition, the first polyolefin layer 12 a and the second polyolefinlayer 12 b may each contain a pigment if necessary. As the pigment,various inorganic pigments can be used. As a specific example of thepigment, carbon (carbon, graphite) exemplified as the filler can bepreferably exemplified. Carbon (carbon, graphite) is a materialgenerally used inside an electrical storage device, and there is nopossibility of being dissolved in an electrolytic solution. In addition,the carbon has a high coloring effect, allows a sufficient coloringeffect to be obtained with an addition amount small enough not to hinderbondability, is not melted by heat, and is capable of increasing theapparent melt viscosity of the resin added. Further, it is possible toimpart an excellent sealing property between the exterior material forelectrical storage devices and the metal terminal by preventing apressed portion from being thinned during thermal bonding(heat-sealing).

When a pigment is added to each of the first polyolefin layer 12 a andthe second polyolefin layer 12 b, for example, the addition amounts ofthe pigments based on 100 parts by mass of resin components forming thefirst polyolefin layer 12 a and the second polyolefin layer 12 b,respectively, are each about 0.05 to 0.3 parts by mass, preferably about0.1 to 0.2 parts by mass, when carbon black having a particle size ofabout 0.03 μm is used. By adding a pigment to the first polyolefin layer12 a and the second polyolefin layer 12 b, the presence or absence ofthe adhesive film 1 for metal terminal can be detected by a sensor, orcan be visually inspected. It is particularly preferable that the firstpolyolefin layer 12 a contains a pigment. When a filler and a pigmentare added to the first polyolefin layer 12 a and the second polyolefinlayer 12 b, the filler and the pigment may be added to the firstpolyolefin layer 12 a and the second polyolefin layer 12 b identically,and from the viewpoint of ensuring that the heat-weldability of theadhesive film 1 for metal terminal, it is preferable that the filler andthe pigment are added separately between the first polyolefin layer 12 aand the second polyolefin layer 12 b.

From the viewpoint of satisfying the above-described martens hardnessand the like and more suitably exhibiting excellent adhesion andexcellent followability of the adhesive film 1 for metal terminal to themetal terminal 2, the melt mass flow rate (MFR) of each of the firstpolyolefin layer 12 a and the second polyolefin layer 12 b at 230° C. ispreferably about 5 g/10 min or more, more preferably about 7 g/10 min ormore, still more preferably about 8 g/10 min or more, and preferablyabout 11 g/10 min or less, more preferably about 10 g/10 min or less,and is preferably in the range of about 5 to 11 g/10 min, about 5 to 10g/10 min, about 7 to 11 g/10 min, about 7 to 10 g/10 min, about 8 to 11g/10 min, or about 8 to 10 g/10 min. The melt mass flow rate (MFR) ofeach of the first polyolefin layer 12 a and the second polyolefin layer12 b is a value (g/10 min) measured at 230° C. in accordance with theprovision of JIS K 7210-1: 2014 (ISO 1133-1: 2011). When the firstpolyolefin layer 12 a is an acid-modified polyolefin layer, it isparticularly preferred that the MFR value of the acid-modifiedpolyolefin layer satisfies the above-described value.

From the viewpoint of satisfying the above-described martens hardnessand the like and more suitably exhibiting excellent adhesion andexcellent followability of the adhesive film 1 for metal terminal to themetal terminal 2, the melting point of the first polyolefin layer 12 ais preferably about 120° C. or higher, more preferably about 130° C. orhigher, and preferably about 160° C. or lower, more preferably about150° C. or lower, and is preferably in the range of about 120 to 160°C., about 120 to 150° C., about 130 to 160° C., or about 130 to 150° C.From the viewpoint of satisfying the above-described martens hardnessand the like and more suitably exhibiting excellent adhesion andexcellent followability of the adhesive film 1 for metal terminal to themetal terminal 2, the melting point of the second polyolefin layer 12 bis preferably about 120° C. or higher, more preferably about 130° C. orhigher, and preferably about 160° C. or lower, more preferably about150° C. or lower, and is preferably in the range of about 120 to 160°C., about 120 to 150° C., about 130 to 160° C., or about 130 to 150° C.The melting point is an endothermic peak measured with a differentialscanning calorimeter (DSC).

From the viewpoint of satisfying the above-described martens hardnessand the like and more suitably exhibiting excellent adhesion andexcellent followability of the adhesive film 1 for metal terminal to themetal terminal 2, the thickness of each of the first polyolefin layer 12a and the second polyolefin layer 12 b is preferably about 10 μm ormore, more preferably about 15 μm or more, still more preferably about20 μm or more, even more preferably about 30 μm or more, and, forexample, about 80 μm or less, preferably about 60 μm or less, morepreferably about 50 μm or less. The thicknesses of each of the firstpolyolefin layer 12 a and the second polyolefin layer 12 b is preferablyin the range of about 10 to 80 μm, about 10 to 60 μm, about 10 to 50 μm,about 15 to 80 μm, about 15 to 60 μm, about 15 to 50 μm, about 20 to 80μm, about 20 to 60 μm, about 20 to 50 μm, about 30 to 80 μm, about 30 to60 μm, or about 30 to 50 μm. As a more specific example, for example,the thickness of each of the first polyolefin layer 12 a and the secondpolyolefin layer 12 b is preferably about 10 to 30 μm when the adhesivefilm 1 for metal terminal according to the present disclosure is usedfor consumer electrical storage devices, and the thickness of each ofthe first polyolefin layer 12 a and the second polyolefin layer 12 b ispreferably about 30 to 80 μm when the adhesive film 1 for metal terminalis used for vehicle-mounted power storage devices.

From the viewpoint of satisfying the above-described martens hardnessand the like and more suitably exhibiting excellent adhesion andexcellent followability of the adhesive film 1 for metal terminal to themetal terminal 2, the ratio of the thickness of the base material 11 tothe total thickness of the first polyolefin layer 12 a and the secondpolyolefin layer 12 b is preferably about 0.3 or more, more preferablyabout 0.4 or more, still more preferably 0.5 or more, and preferablyabout 1.0 or less, more preferably about 0.8 or less, and is preferablyin the range of about 0.3 to 1.0, about 0.3 to 0.8, about 0.4 to 1.0,about 0.4 to 0.8, about 0.5 to 1.0, about 0.5 to 0.8.

When the total thickness of the adhesive film 1 for metal terminal is100%, the ratio of the total thickness of the first polyolefin layer 12a and the second polyolefin layer 12 b is preferably about 30 to 80%,more preferably about 50 to 70%.

[Base Material Layer 11]

In the adhesive film 1 for metal terminal, the base material 11 is alayer that functions as a support for the adhesive film 1 for metalterminal.

The material that forms the base material 11 is not particularly limitedas long as it has an insulation quality. Examples of the material thatforms the base material 11 include polyolefin-based resins,polyamide-based resins, polyester-based resins, epoxy resins, acrylicresins, fluororesins, silicone resins, phenol resins, silicon resins,polyurethane resins, polyether imide, polycarbonate, and mixtures andcopolymers thereof. Among them, polyolefin-based resins are particularlypreferable. That is, the material that forms the base material 11 ispreferably a resin containing a polyolefin backbone such as a polyolefinor an acid-modified polyolefin. The resin forming the base material 1 lcan be confirmed to contain a polyolefin backbone by an analysis methodsuch as infrared spectroscopy or gas chromatography mass spectrometry.

As described above, it is preferable that the base material 11 containsa polyolefin-based resin, more preferably a polyolefin, and it is stillmore preferable that the base material 11 is a layer formed of apolyolefin. Specific examples of the polyolefin include polyethylenesuch as low-density polyethylene, medium-density polyethylene,high-density polyethylene and linear low-density polyethylene;crystalline or noncrystalline polypropylene such as homopolypropylene,block copolymers of polypropylene (e.g. block copolymers of propyleneand ethylene) and random copolymers of polypropylene (e.g. randomcopolymers of propylene and ethylene); terpolymers ofethylene-butene-propylene; and the like. Among these polyolefins,polyethylenes and polypropylene are preferred, with polypropylene beingmore preferred. In addition, it is preferable that the base material 11contains homopolypropylene and it is particularly preferable that thebase material 11 is formed of homopolypropylene because excellentelectrolytic solution resistance is obtained.

Specific examples of the polyamide include aliphatic polyamides such asnylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers ofnylon 6 and nylon 66: hexamethylenediamine-isophthalic acid-terephthalicacid copolymerization polyamides containing a structural unit derivedfrom terephthalic acid and/or isophthalic acid, such as nylon 61, nylon6T, nylon 6IT and nylon 616T (I denotes isophthalic acid and T denotesterephthalic acid), and polyamides containing aromatics, such aspolymethaxylylene adipamide (MXD6); cycloaliphatic polyamides such aspolyaminomethyl cyclohexyl adipamide (PACM 6); polyamides copolymerizedwith a lactam component or an isocyanate component such as4,4′-diphenylmethane-diisocyanate, and polyester amide copolymers andpolyether ester amide copolymers as copolymers of a copolymerizationpolyamide and a polyester or a polyalkylene ether glycol; and copolymersthereof. These polyamides may be used alone, or may be used incombination of two or more thereof.

Specific examples of the polyester include polyethylene terephthalate,polybutylene terephthalate, polyethylene naphthalate, polybutylenenaphthalate, polyethylene isophthalate, copolymerization polyesters withethylene terephthalate as a main repeating unit, and copolymerizationpolyesters with a butylene terephthalate as a main repeating unit.Specific examples of the copolymerization polyester including ethyleneterephthalate as a main repeating unit include copolymer polyesters thatare polymerized with ethylene isophthalate and include ethyleneterephthalate as a main repeating unit (hereinafter, abbreviated asfollows after polyethylene(terephthalate/isophthalate)),polyethylene(terephthalate/isophthalate),polyethylene(terephthalate/adipate), polyethylene(terephthalate/sodiumsulfoisophthalate), polyethylene(terephthalate/sodium isophthalate),polyethylene (terephthalate/phenyl-dicarboxylate) andpolyethylene(terephthalate/decane dicarboxylate). Specific examples ofthe copolymerization polyester with butylene terephthalate as a mainrepeating unit include copolymer polyesters that are polymerized withbutylene isophthalate and include butylene terephthalate as a mainrepeating unit (hereinafter, abbreviated as follows afterpolybutylene(terephthalate/isophthalate)),polybutylene(terephthalate/adipate),polybutylene(terephthalate/sebacate), polybutylene(terephthalate/decanedicarboxylate) and polybutylene naphthalate. These polyesters may beused alone, or may be used in combination of two or more thereof.

In addition, the base material 11 may be formed of a nonwoven fabricformed of any of the resins described above. When the base material 11is a nonwoven fabric, it is preferable that the base material 11 iscomposed of the above-described polyolefin-based resin, polyamide resinor the like.

In addition, a colorant can be blended into the base material 11 so thatthe base material 11 is a layer containing a colorant. In addition, thelight transmittance can be adjusted by selecting a resin having lowtransparency. When the base material 11 is a film, it is also possibleto use a colored film or a film having low transparency. In addition,when the base material 11 is a nonwoven fabric, it is possible to use anonwoven fabric using fibers or a binder containing a colorant, or anonwoven fabric having low transparency.

The melt mass flow rate (MFR) of the base material 11 at 230° C. ispreferably about 8 g/10 min or less, more preferably about 4 g/10 min orless, from the viewpoint of satisfying the above-described martenshardness and the like and more suitably exhibiting excellent adhesionand excellent followability of the adhesive film 1 for metal terminal tothe metal terminal 2, and preferably about 1 g/10 min or more, morepreferably about 2 g/10 min or more, from the viewpoint of ensuring thatthe adhesive film 1 for metal terminal has excellent flexibility (ratedgood in evaluation of followability and adhesion described later), andis preferably in the range of about 1 to 8 g/10 min, about 1 to 4 g/10min, about 2 to 8 g/10 min, or about 2 to 4 g/10 min. When the basematerial 11 is a polyolefin layer (a layer formed of a polyolefin), itis particularly preferred that the MFR value of the polyolefin layersatisfies the above-described value. The melt mass flow rate (MFR) ofthe base material 11 is a value (g/10 min) measured at 230° C. inaccordance with the provision of JIS K 7210-1: 2014 (ISO 1133-1: 2011).

From the viewpoint of satisfying the above-described martens hardnessand the like and more suitably exhibiting excellent adhesion andexcellent followability of the adhesive film 1 for metal terminal to themetal terminal 2, the melting point of the base material 11 ispreferably about 130° C. or higher, more preferably about 150° C. orhigher, and preferably about 190° C. or lower, more preferably about170° C. or lower, and is preferably in the range of about 130 to 190°C., about 130 to 170° C., about 150 to 190° C., or about 150 to 170° C.The melting point is an endothermic peak measured with a differentialscanning calorimeter (DSC).

When the base material 11 is composed of a resin film, a surface of thebase material 11 may be subjected to known easy-adhesive means such ascorona discharge treatment, ozone treatment or plasma treatment ifnecessary.

From the viewpoint of more suitably exhibiting excellent adhesion andexcellent followability of the adhesive film 1 for metal terminal to themetal terminal 2, the thickness of the base material 11 is, for example,about 100 μm or less, preferably about 60 μm or less, more preferablyabout 55 μm or less. In addition, the thickness of the base material 11is preferably about 20 μm or more, more preferably about 30 μm or more,still more preferably about 40 μm or more. The thickness of the basematerial 11 is preferably in the range of about 20 to 100 μm, about 20to 60 μm, about 20 to 55 μm, about 30 to 100 μm, about 30 to 60 μm,about 30 to 55 μm, about 40 to 100 μm, about 40 to 60 μm, or about 40 to55 μm. As a more specific example, for example, the thickness of thebase material 11 is preferably about 30 to 55 μm when the adhesive film1 for metal terminal according to the present disclosure is used forconsumer electrical storage devices, and the thickness of the basematerial 11 is preferably about 40 to 100 μm when the adhesive film 1for metal terminal is used for vehicle-mounted power storage devices.

[Adhesion Promotor Layer 13]

The adhesion promotor layer 13 is a layer provided if necessary for thepurpose of firmly bonding the base material 11 to the first polyolefinlayer 12 a and the second polyolefin layer 12 b (see FIG. 5 ). Theadhesion promotor layer 13 may be provided only on one side or bothsides between the base material 11 and the first polyolefin layer 12 aand second polyolefin layer 12 b.

The adhesion promotor layer 13 can be formed using a known adhesionpromotor such as an isocyanate-based adhesion promotor, apolyethyleneimine-based adhesion promotor, a polyester-based adhesionpromotor, a polyurethane-based adhesion promotor or apolybutadiene-based adhesion promotor. From the viewpoint of furtherimproving electrolytic solution resistance, it is preferable that theadhesion promotor layer is formed of an isocyanate-based adhesionpromotor, among the above-mentioned adhesion promotors. As theisocyanate-based adhesion promotor, one composed of an isocyanatecomponent selected from a triisocyanate monomer and polymeric MDI isexcellent in lamination strength and undergoes little decrease inlamination strength after immersion in an electrolytic solution. Inparticular, it is particularly preferable to form the adhesion promotorlayer from an adhesion promoter composed oftriphenylmethane-4,4′,4″-triisocyanate which is a triisocyanate monomeror polymethylene polyphenyl polyisocyanate which is polymeric MDI (NCOcontent: about 30% and viscosity: 200 to 700 mPa·s). In addition, it isalso preferable to form the adhesion promotor layer fromtris(p-isocyanatephenyl)thiophosphate which is a triisocyanate monomer,or a two-liquid curable adhesion promotor contain apolyethyleneimine-based resin as a main agent and polycarbodiimide as acrosslinking agent.

The adhesion promotor layer 13 can be formed by performing coating by aknown coating method such as a bar coating method, a roll coating methodor a gravure coating method, and drying. The coating amount of theadhesion promotor is about 20 to 100 mg/m², preferably about 40 to 60mg/m² in the case of an adhesion promotor composed of triisocyanate,about 40 to 150 mg/m², preferably about 60 to 100 mg/m2 in the case ofan adhesion promotor composed of polymeric MDI, and about 5 to 50 mg/m²,preferably about 10 to 30 mg/m² in the case of a two-liquid curableadhesion promotor containing polyethyleneimine as a main agent andpolycarbodiimide as a crosslinking agent. The triisocyanate monomer is amonomer having three isocyanate groups per molecule, and the polymericMDI is a mixture of MDI and a MDI oligomer obtained by polymerizing MDI,and is represented by the following formula.

The adhesive film 1 for metal terminal according to the presentdisclosure can be manufactured by, for example, laminating the firstpolyolefin layer 12 a and the second polyolefin layer 12 b on bothsurfaces, respectively, of the base material 11. The base material 11can be laminated to the first polyolefin layer 12 a and the secondpolyolefin layer 12 b by a known method such as an extrusion laminationmethod, a T-die method, an inflation method or a thermal laminationmethod. When the base material 11 is laminated to the first polyolefinlayer 12 a and the second polyolefin layer 12 b with the adhesionpromotor layer 13 interposed therebetween, for example, the adhesionpromotor for forming the adhesion promotor layer 13 may be applied anddried on the base material 11 by the above-described method, followed bylaminating the first polyolefin layer 12 a and the second polyolefinlayer 12 b onto the adhesion promotor layer 13.

The method for interposing the adhesive film 1 for metal terminalbetween the metal terminal 2 and the exterior material 3 for electricalstorage devices is not particularly limited, and for example, as shownin FIGS. 1 to 3 , the adhesive film 1 for metal terminal may be woundaround the metal terminal 2 at a portion where the metal terminal 2 issandwiched between the exterior materials 3 for electrical storagedevices. In addition, the adhesive film 1 for metal terminal may bedisposed on both sides of the metal terminal 2 so as to cross the twometal terminals 2 in a portion where the metal terminal 2 is sandwichedbetween the exterior materials 3 for electrical storage devices.

[Metal Terminal 2]

The adhesive film 1 for metal terminal according to the presentdisclosure is interposed between the metal terminal 2 and the exteriormaterial 3 for electrical storage devices. The metal terminal 2 (tab) isa conductive member electrically connected to an electrode (positiveelectrode or negative electrode) of the electrical storage deviceelement 4, and is composed of a metal material. The metal material thatforms the metal terminal 2 is not particularly limited, and examplesthereof include aluminum, nickel, and copper. For example, the metalterminal 2 connected to a positive electrode of a lithium ion electricalstorage device is typically composed of aluminum or the like. Inaddition, the metal terminal 2 connected to a negative electrode of alithium ion electrical storage device is typically composed of copper,nickel or the like.

From the viewpoint of enhancing electrolytic solution resistance, it ispreferable that the surface of the metal terminal 2 is subjected tochemical conversion treatment. For example, when the metal terminal 2 isformed of aluminum, specific examples of the chemical conversiontreatment include a known method in which a corrosion-resistant film ofa phosphate, a chromate, a fluoride, a triazinethiol compound or thelike. Among the methods for forming a corrosion-resistant film,phosphoric acid chromate treatment using a material including threecomponents: a phenol resin, a chromium (III) fluoride compound andphosphoric acid is preferred.

The size of the metal terminal 2 may be appropriately set according tothe size of an electrical storage device used. The thickness of themetal terminal 2 is preferably about 50 to 1000 μm, more preferablyabout 70 to 800 μm. In addition, the length of the metal terminal 2 ispreferably about 1 to 200 mm, more preferably about 3 to 150 mm. Inaddition, the length of the metal terminal 2 is preferably about 1 to200 mm, more preferably about 3 to 150 mm.

[Exterior Material 3 for Electrical Storage Devices]

Examples of the exterior material 3 for electrical storage devicesinclude materials having a laminated structure including a laminatedbody having at least a base material layer 31, a barrier layer 33, and aheat-sealable resin layer 35 in this order. FIG. 6 shows an aspect inwhich the base material layer 31, an adhesive agent layer 32 provided ifnecessary, the barrier layer 33, an adhesive layer 34 provided ifnecessary, and the heat-sealable resin layer 35 are laminated in thisorder as an example of a cross-sectional structure of the exteriormaterial 3 for electrical storage devices. In the exterior material 3for electrical storage devices, the base material layer 31 is on theouter layer side, and the heat-sealable resin layer 35 is an innermostlayer. During construction of an electrical storage device, theheat-sealable resin layers 35 located on the peripheral edge of theelectrical storage device element 4 is brought into contact with eachother, and heat-welded to seal the electrical storage device element 4,so that the electrical storage device element 4 is encapsulated. FIGS. 1to 3 show the electrical storage device 10 where the embossed-typeexterior material 3 for electrical storage devices, which is molded byembossing molding, is used, but the exterior material 3 for electricalstorage devices may be of non-molded pouch type. Examples of the pouchtype include three-way seal, four-way seal and pillow type, and any ofthe types may be used.

The thickness of the laminated body forming the exterior material 3 forelectrical storage devices is not particularly limited, and ispreferably about 190 μm, about 180 μm or less, about 160 μm or less,about 155 μm or less, about 140 μm or less, about 130 μm or less, orabout 120 μm or less from the viewpoint of cost reduction, improvementof the energy density and the like, and preferably about 35 μm or more,about 45 μm or more, about 60 μm or more, or about 80 μm or more fromthe viewpoint of maintaining the function of the exterior material 3 forelectrical storage devices, which is protection of the electricalstorage device element 4. For example, the thickness is preferably inthe range of about 35 to 190 μm, about 35 to 180 μm, about 35 to 160 μm,about 35 to 155 μm, about 35 to 140 μm, about 35 to 130 μm, about 35 to120 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 160 μm,about 45 to 155 μm, about 45 to 140 μm, about 45 to 130 μm or more,about 45 to 120 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to160 μm, about 60 to 155 μm, about 60 to 140 μm, about 60 to 130 μm,about 60 to 120 μm, about 80 to 190 μm, about 80 to 180 μm, about 80 to160 μm, about 80 to 155 μm, about 80 to 140 μm, about 80 to 130 μm orabout 80 to 120 μm.

[Base Material Layer 31]

In the exterior material 3 for electrical storage devices, the basematerial layer 31 is a layer that functions as a base material of theexterior material for electrical storage devices, and forms theoutermost layer side of the exterior material for electrical storagedevices.

The material that forms the base material layer 31 is not particularlylimited as long as it has an insulation quality. Examples of thematerial that forms the base material layer 31 include polyester,polyamide, epoxy, acrylic, fluororesins, polyurethane, silicone resins,phenol, polyetherimide, polyimide and mixtures and copolymers thereof.Polyester such as polyethylene terephthalate or polybutyleneterephthalate has the advantage that it is excellent in electrolyticsolution resistance, so that whitening etc. due to deposition of anelectrolytic solution is hard to occur, and thus the polyester issuitably used as a material for formation of the base material layer 31.In addition, a polyamide film is excellent in stretchability, canprevent occurrence of whitening due to resin breakage in the basematerial layer 31 during molding, and is thus suitably used as amaterial for formation of the base material layer 31.

The base material layer 31 may be formed of a uniaxially or biaxiallystretched resin film, or may be formed of an unstretched resin film.Among them, a uniaxially or biaxially stretched resin film, particularlya biaxially stretched resin film has improved heat resistance throughorientation and crystallization, and is therefore suitably used as thebase material layer 31.

Among them, nylons and polyesters are preferable and biaxially stretchednylons and biaxially stretched polyesters are more preferable as resinfilms for formation of the base material layer 31.

The base material layer 31 can also be laminated with a resin film whichis made of a different material for improving pinhole resistance, andinsulation quality as a packaging of an electrical storage device.Specific examples include a multilayer structure in which a polyesterfilm and a nylon film are laminated, and a multilayer structure in whicha biaxially stretched polyester and a biaxially stretched nylon arelaminated. When the base material layer 31 is made to have a multilayerstructure, the resin films may be bonded with the use of an adhesive, ormay be directly laminated without the use of an adhesive. Examples ofthe method for bonding the resin films without the use of an adhesiveinclude methods in which the resin films are bonded in a heat-meltedstate, such as a co-extrusion method, a sand lamination method and athermal lamination method.

In addition, the friction of the base material layer 31 may be reducedfor improving moldability. When the friction of the base material layer31 is reduced, the friction coefficient of the surface thereof is notparticularly limited, and it is, for example, 1.0 or less. Examples ofthe method for reducing the friction of the base material layer 31include matting treatment, formation of a thin film layer of a slippingagent, and a combination thereof.

The thickness of the base material layer 31 is, for example, about 10 to50 μm, preferably about 15 to 30 μm.

(Adhesive Agent Layer 32)

In the exterior material 3 for electrical storage devices, the adhesiveagent layer 32 is a layer disposed on the base material layer 31 ifnecessary for imparting adhesion to the base material layer 31. That is,the adhesive agent layer 32 is provided between the base material layer31 and the barrier layer 33.

The adhesive agent layer 32 is formed from an adhesive capable ofbonding the base material layer 31 and the barrier layer 33. Theadhesive used for forming the adhesive agent layer 32 may be atwo-liquid curable adhesive, or may be a one-liquid curable adhesive. Inaddition, the adhesion mechanism of the adhesive used for forming theadhesive agent layer 32 is not particularly limited, and may be any oneof a chemical reaction type, a solvent volatilization type, a heatmelting type, a heat pressing type and so on.

As resin components of adhesives that can be used for formation of theadhesive agent layer 32, polyurethane-based two-liquid curable adhesiveagents; and polyamides, polyesters or blend resins of these resins andmodified polyolefins are preferable because they are excellent inspreadability, durability and a yellowing inhibition action underhigh-humidity conditions, a thermal degradation inhibition action duringheat-sealing, and so on, and effectively suppress occurrence ofdelamination by inhibiting a reduction in lamination strength betweenthe base material layer 31 and the barrier layer 33.

The adhesive agent layer 32 may be made multilayered with differentadhesive components. When the adhesive agent layer 32 is mademultilayered with different components, it is preferable that a resinexcellent in bondability to the base material layer 31 is selected as anadhesive component to be disposed on the base material layer 31 side,and an adhesive component excellent in bondability to the barrier layer33 is selected as an adhesive component to be disposed on the barrierlayer 33 side, from the viewpoint of improving lamination strengthbetween the base material layer 31 and the barrier layer 33. When theadhesive agent layer 32 is made multilayered with different adhesivecomponents, specific examples of the preferred adhesive component to bedisposed on the barrier layer 33 side include acid-modified polyolefins,metal-modified polyolefins, mixed resins of polyesters and acid-modifiedpolyolefins, and resins containing a copolymerization polyester.

The thickness of the adhesive agent layer 32 is, for example, about 2 to50 μm, preferably about 3 to 25 μm.

(Barrier Layer 33)

In the exterior material for electrical storage devices, the barrierlayer 33 is a layer which is intended to improve the strength of theexterior material for electrical storage devices and which has afunction of preventing ingress of water vapor, oxygen, light and thelike into the electrical storage device. The barrier layer 33 ispreferably a metal layer, i.e. a layer formed of a metal. Specificexamples of the metal forming the barrier layer 33 include aluminum,stainless and titanium, with aluminum being preferred. The barrier layer33 can be formed from, for example, a metal foil, a metalvapor-deposited film, an inorganic oxide vapor-deposited film, acarbon-containing inorganic oxide vapor-deposited film, a film providedwith any of these vapor-deposited films, or the like, and is formedpreferably from a metal foil, more preferably from an aluminum foil.From the viewpoint of preventing generation of wrinkles and pinholes inthe barrier layer 33 during manufacturing of the exterior material forelectrical storage devices, it is more preferable to form the barrierlayer from a soft aluminum foil such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160: 1994 A8079H-O, JIS H4000:2014 A8021P-O, JISH4000:2014 A8079P-O).

The thickness of the barrier layer 33 is preferably about 10 to 200 μm,more preferably about 20 to 100 μm, from the viewpoint of makingpinholes less likely to be generated by molding while thinning theexterior material for electrical storage devices.

In addition, at least one surface, preferably both surfaces, of thebarrier layer 33 are subjected to a chemical conversion treatment forstabilization of bonding, prevention of dissolution and corrosion, andso on. Here, the chemical conversion treatment is a treatment forforming a corrosion-resistant film on the surface of the barrier layer.

(Adhesive Layer 34)

In the exterior material 3 for electrical storage devices, the adhesivelayer 34 is a layer provided between the barrier layer 33 and theheat-sealable resin layer 35 if necessary for firmly bonding theheat-sealable resin layer 35.

The adhesive layer 34 is formed from an adhesive capable of bonding thebarrier layer 33 and the heat-sealable resin layer 35 to each other. Thecomposition of the adhesive used for forming the adhesive layer is notparticularly limited, and examples thereof include resin compositionscontaining an acid-modified polyolefin. Examples of the acid-modifiedpolyolefin include those identical to the acid-modified polyolefinsexemplified for the first polyolefin layer 12 a and the secondpolyolefin layer 12 b.

The thickness of the adhesive layer 34 is, for example, about 1 to 40μm, preferably about 2 to 30 μm.

(Heat-Sealable Resin Layer 35)

In the exterior material 3 for electrical storage devices, theheat-sealable resin layer 35 is a layer which corresponds to aninnermost layer and performs a function of hermetically sealing theelectrical storage device element by heat-sealing the heat-sealableresin layer during construction of the electrical storage device.

The resin component to be used in the heat-sealable resin layer 35 isnot particularly limited as long as it can be heat-welded, and examplesthereof include polyolefins and cyclic polyolefins.

Specific examples of the polyolefin include polyethylene such aslow-density polyethylene, medium-density polyethylene, high-densitypolyethylene and linear low-density polyethylene; crystalline ornoncrystalline polypropylene such as homopolypropylene, block copolymersof polypropylene (e.g. block copolymers of propylene and ethylene) andrandom copolymers of polypropylene (e.g. random copolymers of propyleneand ethylene); terpolymers of ethylene-butene-propylene; and the like.Among these polyolefins, polyethylene and polypropylene are preferred.

The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer,and examples of the olefin as a constituent monomer of the cyclicpolyolefin include ethylene, propylene, 4-methyl-1-pentene, butadieneand isoprene. Examples of the cyclic monomer as a constituent monomer ofthe cyclic polyolefin include cyclic alkenes such as norbornene,specifically cyclic dienes such as cyclopentadiene, dicyclopentadiene,cyclohexadiene and norbornadiene. Among these polyolefins, cyclicalkenes are preferable, and norbornene is further preferable. Examplesof the constituent monomer include styrene.

Among these resin components, crystalline or noncrystalline polyolefins,cyclic polyolefins and blend polymers thereof are preferable, andpolyethylene, polypropylene, copolymers of ethylene and norbornene, andblend polymers of two or more thereof are more preferable.

The heat-sealable resin layer 35 may be formed from one resin componentalone, or may be formed from a blend polymer obtained by combining twoor more resin components. Further, the heat-sealable resin layer 35 maybe formed of only one layer, but may be formed of two or more layerswith the same resin component or different resin components. It isparticularly preferable that the second polyolefin layer 12 b and theheat-sealable resin layer 35 have the same resin because adhesionbetween these layers is improved.

The thickness of the heat-sealable resin layer 35 is not particularlylimited, and is, for example, about 2 to 2000 μm, preferably about 5 to1000 μm, still more preferably about 10 to 500 μm.

2. Electrical Storage Device

The electrical storage device 10 of the present disclosure includes theelectrical storage device element 4 including at least a positiveelectrode, a negative electrode and an electrolyte; the exteriormaterial 3 for electrical storage devices that seals the electricalstorage device element 4; and the metal terminal 2 electricallyconnected to each of the positive electrode and the negative electrodeand protruding to the outside of the exterior material 3 for electricalstorage devices. In the electrical storage device 10 of the presentdisclosure, the adhesive film 1 for metal terminal according to thepresent disclosure is interposed between the metal terminal 2 and theexterior material 3 for electrical storage devices. That is, theelectrical storage device 10 of the present disclosure can bemanufactured by a method including the step of interposing the adhesivefilm 1 for metal terminal according to the present disclosure betweenthe metal terminal 2 and the exterior material 3 for electrical storagedevices.

Specifically, the electrical storage device element 4 including at leasta positive electrode, a negative electrode and an electrolyte is coveredwith the exterior material 3 for electrical storage devices such that aflange portion (a region where the heat-sealable resin layers 35 contacteach other, the region being a peripheral edge portion 3 a of theexterior material for electrical storage devices) of the exteriormaterial for electrical storage devices can be formed on the peripheraledge of the electrical storage device element 4, where the adhesive film1 for metal terminal according to the present disclosure is interposedbetween the metal terminal 2 and the heat-sealable resin layer 35 whilethe metal terminal 2 connected to each of the positive electrode and thenegative electrode protrudes to the outside, and the heat-sealable resinlayers 35 at the flange portion are heat-sealed to each other, therebyproviding the electrical storage device 10 using the exterior material 3for electrical storage devices. When the electrical storage deviceelement 4 is stored using the exterior material 3 for electrical storagedevices, the heat-sealable resin layer 35 of the exterior material 3 forelectrical storage devices is on the inner side (a surface contactingthe electrical storage device element 4).

The exterior material for electrical storage devices according to thepresent disclosure can be suitably used for electrical storage devicessuch as batteries (including condensers, capacitors and the like). Theexterior material for electrical storage devices according to thepresent disclosure may be used for either primary batteries or secondarybatteries, and is preferably used for secondary batteries. The type of asecondary battery to which the exterior material for electrical storagedevices according to the present disclosure is applied is notparticularly limited, and examples thereof include lithium ionbatteries, lithium ion polymer batteries, solid-state batteries, leadstorage batteries, nickel-hydrogen storage batteries, nickel-cadmiumstorage batteries, nickel-iron storage batteries, nickel-zinc storagebatteries, silver oxide-zinc storage batteries, metal-air batteries,polyvalent cation batteries, condensers and capacitors. Of thesesecondary batteries, preferred subjects to which the exterior materialfor electrical storage devices according to the present disclosure isapplied include lithium ion batteries and lithium ion polymer batteries.

EXAMPLES

Hereinafter, the present disclosure will be described in detail by wayof examples and comparative examples. However, the present disclosure isnot limited to examples.

<Manufacturing of Adhesive Film for Metal Terminal>

Example 1

Maleic anhydride-modified polypropylene (PPa) was provided as apolyolefin for forming a first polyolefin layer, polypropylene (PP) wasprovided as a polyolefin for forming a second polyolefin layer, and anunstretched polypropylene film (CPP, homopolypropylene, thickness: 50μm) was provided as a base material. As a material for forming the firstpolyolefin layer, a particularly highly flexible material, which had notbeen used for conventional adhesive films for metal terminal, was usedso that the layer had a martens hardness, an indentation elastic modulusand a depth of indentation ha as described in Table 1. Maleicanhydride-modified polypropylene (PPa) was extruded onto one surface ofthe base material (CPP) by a T-die extruder to form a firstpolypropylene layer (thickness: 50 μm), and polypropylene (PP) wasextruded onto the other surface of the base material (CPP) by a T-dieextruder to form a second polypropylene layer (thickness: 50 μm),thereby obtaining an adhesive film for metal terminal in which a firstpolyolefin layer (50 μm, PPa layer), a base material (50 μm, CPP layer)and a second polyolefin layer (50 μm, PP layer) were laminated in thisorder.

Example 2

Maleic anhydride-modified polypropylene (PPa) colored black with carbonblack was provided as a polyolefin for forming a first polyolefin layer,polypropylene (PP) was provided as a polyolefin for forming a secondpolyolefin layer, and an unstretched polypropylene film (CPP,homopolypropylene, thickness: 50 μm) was provided as a base material. Asa material for forming the first polyolefin layer, a highly flexiblematerial, which had not been used for conventional adhesive films formetal terminal, was used so that the layer had a martens hardness, anindentation elastic modulus and a depth of indentation has as describedin Table 1. Maleic anhydride-modified polypropylene (PPa) colored blackwith carbon black was extruded onto one surface of the base material(CPP) by a T-die extruder to form a first polypropylene layer(thickness: 50 μm), and polypropylene (PP) was extruded onto the othersurface of the base material (CPP) by a T-die extruder to form a secondpolypropylene layer (thickness: 50 μm), thereby obtaining an adhesivefilm for metal terminal in which a first polyolefin layer (50 μm, PPalayer), a base material (50 μm, CPP layer) and a second polyolefin layer(50 μm, PP layer) were laminated in this order.

Example 3

Maleic anhydride-modified polypropylene (PPa) as a polyolefin forforming a first polyolefin layer, polypropylene (PP) was provided as apolyolefin for forming a second polyolefin layer, and a polypropylenefilm (PP) colored black with carbon black was provided as a basematerial. As materials for forming the first polyolefin layer and thebase material, highly flexible materials, which had not been used forconventional adhesive films for metal terminal, was used so that each ofthese layers had the martens hardness, the indentation elastic modulusand the depth of indentation h_(max) described in Table 1. Polypropylene(PP) was extruded by a T-die extruder to form a base material(thickness: 30 μm), maleic anhydride-modified polypropylene (PPa) wasextruded onto one surface of the base material (PP) by a T-die extruderto form a first polypropylene layer (thickness: 50 m), and polypropylene(PP) was extruded onto the other surface of the base material (PP,thickness: 30 μm) by a T-die extruder to form a second polypropylenelayer (thickness: 20 μm), thereby obtaining an adhesive film for metalterminal in which a first polyolefin layer (50 μm, PPa layer), a basematerial (30 μm, PP layer) and a second polyolefin layer (20 μm, PPlayer) were laminated in this order.

Comparative Example 1

Maleic anhydride-modified polypropylene (PPa) was provided as apolyolefin for forming a first polyolefin layer, maleicanhydride-modified polypropylene (PPa) was provided as a polyolefin forforming a second polyolefin layer, and polypropylene (PP,homopolypropylene) was provided as a base material. Using the resins forthe layers, multilayer air-cooling inflation molding was performed toobtain an adhesive film for metal terminal in which a first polyolefinlayer (50 μm, PPa layer), a base material (50 μm, PP layer) and a secondpolyolefin layer (50 μm, PPa layer) were laminated in this order.

Comparative Example 2

Maleic anhydride-modified polypropylene (PPa) was provided as apolyolefin for forming a first polyolefin layer, maleicanhydride-modified polypropylene (PPa) was provided as a polyolefin forforming a second polyolefin layer, and polypropylene (PP,homopolypropylene) was provided as a base material. Using the resins forthe layers, multilayer air-cooling inflation molding was performed toobtain an adhesive film for metal terminal in which a first polyolefinlayer (35 μm, PPa layer), a base material (80 μm, PP layer) and a secondpolyolefin layer (35 μm, PPa layer) were laminated in this order.

The martens hardness, the indentation elastic modulus and the depth ofindentation h_(max) of each of the layers of the adhesive films formetal terminal shown in Table 1 can be adjusted by the composition,backbone, dispersibility, molecular weight, melting point and MFR of theresin forming each layer, and conditions (e.g. the extrusion width fromthe T-die, the draw ratio, the draw speed and the heat treatmenttemperature) of a T-die and inflation in manufacturing of the adhesivefilm 1 for metal terminal. For the martens hardness, the indentationelastic modulus, and the depth of indentation h_(max) of the firstpolyolefin layer of each of the adhesive films for metal terminal shownin Table 1, the flexibility was adjusted by adding a butene component,an ethylene-propylene-butene copolymer, a noncrystallineethylene-propylene copolymer, a propylene-α-olefin copolymer or thelike.

<Measurement of martens hardness, indentation elastic modulus and depthof indentation h_(max)>

The martens hardness, the indentation elastic modulus, and the depth ofindentation h_(max) of each of the first polyolefin layer, the basematerial and the second polyolefin layer of each of the adhesive filmsfor metal terminal of examples and comparative examples were measured.In the measurements, the adhesive film for metal terminal was cut to 30mm in MD and 15 mm in TD as pretreatment of a sample to be measured.Next, the sample was embedded in epoxy cold implant resin and dried forabout 1 day. Thereafter, using a mechanical polishing apparatusTegrapol-35 manufactured by Marumoto Struers K.K., a cross-sectionobtained by cutting in a transverse direction was polished to set thesurface roughness of the cross-section of the sample to about 1.0 μm.The measurement by an indentation method was performed using PICODENTORHM-500 manufactured by FISCHER INSTRUMENTS K.K. The measurement wasperformed in a direction perpendicular to a thickness-directioncross-section (central part in the thickness direction) of a layer to bemeasured. The cross-section to be measured is a cross-section obtainedby cutting the adhesive film for metal terminal in a transversedirection and subjected to the pretreatment. The measurement conditionsare as follows.

(Measurement conditions)

A load of 10 mN.

A load application speed of 1 mN/10 seconds.

A retention time of 10 seconds.

A load releasing speed of 1 mN/10 seconds.

Indenter: Vickers indenter in which the facing angle of a regularquadrangular pyramid-shaped tip end portion is 136°.

A measurement temperature of 25° C.

Measured value: an average of a total of eight measured values obtainedby measuring ten times with the measurement location changed each time,and then excluding one maximum value and one minimum value.

For reference, an image diagram of a graph showing a relationshipbetween a depth of indentation (μm) and a load (mN) which is obtained bymeasuring a martens hardness, an indentation elastic modulus, and adepth of indentation h_(max) as described above is shown in FIG. 8 .

The martens hardness is calculated in accordance with the followingexpression.

HM (martens hardness)=maximum load F (N)/surface area (mm²) of indenterdetermined from depth of indentation=maximum load F(N)/26.43 h ²

F: maximum load (N)

h: depth of indentation under test load=h_(max) (value at point E inFIG. 8 (intersection between perpendicular line drawn from point C and Yaxis))

In addition, the indentation elastic modulus is calculated from agradient of a tangent line C-D in FIG. 8 . In addition, the depth ofindentation h_(max) is calculated from the value at point E in FIG. 8 .

<Measurement of adhesion strength between adhesive film for metalterminal and metal terminal>

As a metal terminal, aluminum (JIS H 4160: 1994 A 8079 H-O) having alength of 50 mm, a width of 22.5 mm and a thickness of 200 μm wasprovided. Each of the adhesive films for metal terminal, which had beenobtained in examples and comparative examples, was cut to a length of 45mm and a width of 15 mm. Next, the adhesive film for metal terminal wasplaced on the metal terminal to obtain a laminated body of a metalterminal and an adhesive film. Here, the lamination was performed insuch a manner that the longitudinal direction and the lateral directionof the metal terminal coincided with the length direction and the widthdirection of the adhesive film for metal terminal, respectively, and thecenters of the metal terminal and the adhesive film for metal terminalcoincided with each other. Next, with a tetrafluoroethylene-ethylenecopolymer film (ETFE film, thickness 100 μm) placed on the adhesive filmfor metal terminal of the laminated body (with the ETFE film coveringthe a surface of the adhesive film for metal terminal), the laminatedbody was put on a hot plate heated to 190° C. (the metal terminal was onthe hot plate side), a 500 g weight with sponge was put thereon, and thelaminated body was left standing for 12 seconds to heat-weld theadhesive film to the metal terminal. The laminated body after theheat-welding was naturally cooled to 25° C. Next, the adhesive film formetal terminal was peeled off from the metal terminal in an environmentat 25° C. using Tensilon Versatile Material Tester (RTG-1210manufactured by A&D Company, Limited). The maximum strength during thepeeling was defined as adhesion strength to the metal terminal (N/15mm). The peeling speed was 50 mm/min, the peeling angle was 180°, andthe distance between chucks was 30 mm. An average of the values of threemeasurements was adopted. The treatment in which the laminated body isleft standing for 12 seconds in a heating and pressurizing environmentat a temperature of 190° C. and a surface pressure of 0.016 MPasimulates heat and pressure applied in the temporary bonding step andthe primary bonding step. Table 1 shows the results.

<Evaluation of followability (adhesive film/metal terminal)>

As a metal terminal, aluminum foil (JIS H 4160: 1994 A 8079 H-O) havinga length of 50 mm, a width of 22.5 mm and a thickness of 400 μm wasprovided. In addition, each of the adhesive films for metal terminalwhich had been obtained in examples and comparative examples (length: 45mm and width: 15 mm) was provided. Next, the metal terminal wassandwiched between the two adhesive films to obtain a laminated body ofan adhesive film, a metal terminal and an adhesive film. Here, thelongitudinal direction of the metal terminal and the width direction ofthe adhesive film for metal terminal are made to coincide with eachother, and the overlapping region has a size of 22.5 mm×15 mm. Next,with the laminated body sandwiched between twotetrafluoroethylene-ethylene copolymer films (ETFE film, thickness 100μm), the laminated body was put on a hot plate heated to 190° C., a 500g weight with sponge was put thereon (a pressure of 0.015 MPa wasapplied), and the laminated body was left standing for 12 seconds toheat-weld the adhesive film to the metal terminal. Here, as shown in theschematic view of FIG. 7 , the metal terminal was sandwiched between theadhesive films to form a portion in which the periphery of the metalterminal was covered with the adhesive film and the two adhesive filmswere heat-welded to each other. The laminated body after theheat-welding was naturally cooled to 25° C., and a thickness-directioncross-section (see region M surrounded by a dashed line circle in FIG. 7) was observed with a laser microscope to evaluate the followability ofthe adhesive film for metal terminal to the shape of the metal terminalin accordance with the following criteria. Table 1 shows the results.

A: There are no air bubbles between the adhesive film for metal terminaland the metal terminal.

B: There are no air bubbles at the interface between the adhesive filmfor metal terminal and the metal terminal, but there are air bubbles inthe adhesive film for metal terminal near the interface.

B⁻: There are air bubbles at the interface between the adhesive film formetal terminal and the metal terminal, but there are no air bubbles inthe adhesive film for metal terminal near the interface.

C: There are air bubbles at the interface between the adhesive film formetal terminal and the metal terminal, and in the adhesive film formetal terminal near the interface.

TABLE 1 Indentation Adhesion Martens elastic Depth of strength toEvaluation hardness modulus indentation metal terminal of Resin (N/mm²)(MPa) h_(max)(μm) (N/15 mm) followability Example 1 First polyolefinlayer PPa 10.6 177.8 6.2 45 A Base material CPP 43.3 748.5 3.0 Secondpolyolefin layer PP 42.0 743.0 3.1 Example 2 First polyolefin layer PPa20.3 389.6 4.5 44 B Base material CPP 31.4 660.2 3.7 Second polyolefinlayer PP 32.6 622.7 3.5 Example 3 First polyolefin layer PPa 17.0 338.64.8 28 B Base material PP 17.4 327.8 4.8 Second polyolefin layer PP 37.31067.8 3.3 Comparative First polyolefin layer PPa 35.2 756.1 3.3 29 CExample 1 Base material PP 69.8 1625.5 2.4 Second polyolefin layer PPa35.2 756.1 3.3 Comparative First polyolefin layer PPa 41.0 864.1 3.1 45C Example 2 Base material PP 50.5 1067.1 2.8 Second polyolefin layer PPa41.0 864.1 3.1

The adhesive films for metal terminal in Examples 1 to 3 have a martenshardness of 30 N/mm² or less as measured in a direction perpendicular toa thickness-direction cross-section of the first polyolefin layer. Theadhesive films for metal terminal in Example 1-3 have excellent adhesionand excellent followability to a metal terminal.

As described above, the present disclosure provides inventions ofaspects as described below.

Item 1. An adhesive film for metal terminal, which is interposed betweena metal terminal electrically connected to an electrode of an electricalstorage device element and an exterior material for electrical storagedevices that seals the electrical storage device element, in which theadhesive film for metal terminal includes a laminated body including, inthe following order: a first polyolefin layer disposed on the metalterminal side, a base material; and a second polyolefin layer disposedon the side of the exterior material for electrical storage devices, and

a martens hardness measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer is 30N/mm² or less under the following measurement conditions:

<martens hardness measurement conditions>

a load of 10 mN;

a load application speed of 1 mN/10 seconds;

a retention time of 10 seconds;

a load releasing speed of 1 mN/10 seconds;

indenter: Vickers indenter in which the facing angle of a regularquadrangular pyramid-shaped tip end portion is 136°;

a measurement temperature of 25° C.; and

measured value: an average of a total of eight measured values obtainedby measuring ten times with the measurement location changed each time,and then excluding one maximum value and one minimum value.

Item 2. The adhesive film for metal terminal according to item 1, inwhich an indentation elastic modulus measured in a directionperpendicular to a thickness-direction cross-section of the firstpolyolefin layer is 400 MPa or less under the martens hardnessmeasurement conditions.

Item 3. The adhesive film for metal terminal according to item 1 or 2,in which a martens hardness measured in a direction perpendicular to athickness-direction cross-section of the base material is 60 N/mm² orless under the martens hardness measurement conditions.

Item 4. The adhesive film for metal terminal according to any one ofitems 1 to 3, in which a martens hardness measured in a directionperpendicular to a thickness-direction cross-section of the secondpolyolefin layer is 60 N/mm² or less under the martens hardnessmeasurement conditions.

Item 5. The adhesive film for metal terminal according to any one ofitems 1 to 4, in which a thickness of the first polyolefin layer is 60μm or less.

Item 6. The adhesive film for metal terminal according to any one ofitems 1 to 5, in which a thickness of the base material is 60 μm orless.

Item 7. The adhesive film for metal terminal according to any one ofitems 1 to 6, in which a thickness of the second polyolefin layer is 60μm or less.

Item 8. The adhesive film for metal terminal according to any one ofitems 1 to 7, in which a thickness of the adhesive film for metalterminal is 180 μm or less.

Item 9. The adhesive film for metal terminal according to any one ofitems 1 to 8, in which a depth of indentation h_(max) at a load of 10mN, which is measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer, is 4.0μm or more under the martens hardness measurement conditions.

Item 10. The adhesive film for metal terminal according to any one ofitems 1 to 9, in which an indentation elastic modulus measured in adirection perpendicular to a thickness-direction cross-section of thebase material is 1000 MPa or less under the martens hardness measurementconditions.

Item 11. The adhesive film for metal terminal according to any one ofitems 1 to 10, in which the first polyolefin layer contains a pigment.

Item 12. The adhesive film for metal terminal according to any one ofitems 1 to 11, in which the base material contains a polyolefinbackbone.

Item 13. A method for manufacturing an adhesive film for metal terminal,which is interposed between a metal terminal electrically connected toan electrode of an electrical storage device element and an exteriormaterial for electrical storage devices that seals the electricalstorage device element,

in which the adhesive film for metal terminal includes a laminated bodyincluding, in the following order: a first polyolefin layer disposed onthe metal terminal side; a base material; and a second polyolefin layerdisposed on the side of the exterior material for electrical storagedevices,

the method includes the step of preparing a laminated body including thefirst polyolefin layer, the base material and the second polyolefinlayer in this order, and

a martens hardness measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer is 30N/mm² or less under the following measurement conditions:

<martens hardness measurement conditions>

a load of 10 mN;

a load application speed of 1 mN/10 seconds;

a retention time of 10 seconds;

a load releasing speed of 1 mN/10 seconds;

indenter: Vickers indenter in which the facing angle of a regularquadrangular pyramid-shaped tip end portion is 136°;

a measurement temperature of 25° C.; and

measured value: an average of a total of eight measured values obtainedby measuring ten times with the measurement location changed each time,and then excluding one maximum value and one minimum value.

Item 14. A metal terminal with an adhesive film for metal terminal inwhich the adhesive film for metal terminal according to any one of items1 to 12 is attached to a metal terminal.

Item 15. An electrical storage device including: the electrical storagedevice element including at least a positive electrode, a negativeelectrode and an electrolyte; the exterior material for electricalstorage devices that seals the electrical storage device element; andthe metal terminal electrically connected to each of the positiveelectrode and the negative electrode and protruding to the outside ofthe exterior material for electrical storage devices, in which theadhesive film for metal terminal according to any one of items 1 to 12is interposed between the metal terminal and the exterior material forelectrical storage devices.

Item 16. A method for manufacturing an electrical storage deviceincluding: the electrical storage device element including at least apositive electrode, a negative electrode and an electrolyte; theexterior material for electrical storage devices that seals theelectrical storage device element; and the metal terminal electricallyconnected to each of the positive electrode and the negative electrodeand protruding to the outside of the exterior material for electricalstorage devices, the method including the step of interposing theadhesive film for metal terminal according to any one of items 1 to 12between the metal terminal and the exterior material for electricalstorage devices, and sealing the electrical storage device element withthe exterior material for electrical storage devices.

DESCRIPTION OF REFERENCE SIGNS

-   -   1: Adhesive film for metal terminal    -   2: Metal terminal    -   3: Exterior material for electrical storage devices    -   3 a: Peripheral edge portion of exterior material for electrical        storage devices    -   4: Electrical storage device element    -   10: Electrical storage device    -   11: Base material    -   12 a: First polyolefin layer    -   12 b: Second polyolefin layer    -   13: Adhesion promotor layer    -   31: Base material layer    -   32: Adhesive agent layer    -   33: Barrier layer    -   34: Adhesive layer    -   35: Heat-sealable resin layer

1. An adhesive film for metal terminal, which is interposed between ametal terminal electrically connected to an electrode of an electricalstorage device element and an exterior material for electrical storagedevices that seals the electrical storage device element, wherein theadhesive film for metal terminal includes a laminated body including, inthe following order: a first polyolefin layer disposed on the metalterminal side; a base material; and a second polyolefin layer disposedon the side of the exterior material for electrical storage devices, anda martens hardness measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer is 30N/mm² or less under the following measurement conditions: <martenshardness measurement conditions> a load of 10 mN; a load applicationspeed of 1 mN/10 seconds; a retention time of 10 seconds; a loadreleasing speed of 1 mN/10 seconds; indenter: Vickers indenter in whichthe facing angle of a regular quadrangular pyramid-shaped tip endportion is 136°; a measurement temperature of 25° C.; and measuredvalue: an average of a total of eight measured values obtained bymeasuring ten times with the measurement location changed each time, andthen excluding one maximum value and one minimum value.
 2. The adhesivefilm for metal terminal according to claim 1, wherein an indentationelastic modulus measured in a direction perpendicular to athickness-direction cross-section of the first polyolefin layer is 400MPa or less under the martens hardness measurement conditions.
 3. Theadhesive film for metal terminal according to claim 1, wherein a martenshardness measured in a direction perpendicular to a thickness-directioncross-section of the base material is 60 N/mm² or less under the martenshardness measurement conditions.
 4. The adhesive film for metal terminalaccording to claim 1, wherein a martens hardness measured in a directionperpendicular to a thickness-direction cross-section of the secondpolyolefin layer is 60 N/mm² or less under the martens hardnessmeasurement conditions.
 5. The adhesive film for metal terminalaccording to claim 1, wherein a thickness of the first polyolefin layeris 60 μm or less.
 6. The adhesive film for metal terminal according toclaim 1, wherein a thickness of the base material is 60 μm or less. 7.The adhesive film for metal terminal according to claim 1, wherein athickness of the second polyolefin layer is 60 μm or less.
 8. Theadhesive film for metal terminal according to claim 1, wherein athickness of the adhesive film for metal terminal is 180 μm or less. 9.The adhesive film for metal terminal according to claim 1, wherein adepth of indentation h_(max) at a load of 10 mN, which is measured in adirection perpendicular to a thickness-direction cross-section of thefirst polyolefin layer, is 4.0 μm or more under the martens hardnessmeasurement conditions.
 10. The adhesive film for metal terminalaccording to claim 1, wherein an indentation elastic modulus measured ina direction perpendicular to a thickness-direction cross-section of thebase material is 1000 MPa or less under the martens hardness measurementconditions.
 11. The adhesive film for metal terminal according to claim1, wherein the first polyolefin layer contains a pigment.
 12. Theadhesive film for metal terminal according to claim 1, wherein the basematerial contains a polyolefin backbone.
 13. A method for manufacturingan adhesive film for metal terminal, which is interposed between a metalterminal electrically connected to an electrode of an electrical storagedevice element and an exterior material for electrical storage devicesthat seals the electrical storage device element, wherein the adhesivefilm for metal terminal includes a laminated body including, in thefollowing order: a first polyolefin layer disposed on the metal terminalside; a base material; and a second polyolefin layer disposed on theside of the exterior material for electrical storage devices, the methodcomprises the step of preparing a laminated body including the firstpolyolefin layer, the base material and the second polyolefin layer inthis order, and a martens hardness measured in a direction perpendicularto a thickness-direction cross-section of the first polyolefin layer is30 N/mm² or less under the following measurement conditions: <martenshardness measurement conditions> a load of 10 mN; a load applicationspeed of 1 mN/10 seconds; a retention time of 10 seconds; a loadreleasing speed of 1 mN/10 seconds; indenter: Vickers indenter in whichthe facing angle of a regular quadrangular pyramid-shaped tip endportion is 136°; a measurement temperature of 25° C.; and measuredvalue: an average of a total of eight measured values obtained bymeasuring ten times with the measurement location changed each time, andthen excluding one maximum value and one minimum value.
 14. A metalterminal with an adhesive film for metal terminal, wherein the adhesivefilm for metal terminal according to claim 1 is attached to a metalterminal.
 15. An electrical storage device comprising: the electricalstorage device element including at least a positive electrode, anegative electrode and an electrolyte; the exterior material forelectrical storage devices that seals the electrical storage deviceelement; and the metal terminal electrically connected to each of thepositive electrode and the negative electrode and protruding to theoutside of the exterior material for electrical storage devices, whereinthe adhesive film for metal terminal according to claim 1 is interposedbetween the metal terminal and the exterior material for electricalstorage devices.
 16. A method for manufacturing an electrical storagedevice including: the electrical storage device element including atleast a positive electrode, a negative electrode and an electrolyte; theexterior material for electrical storage devices that seals theelectrical storage device element; and the metal terminal electricallyconnected to each of the positive electrode and the negative electrodeand protruding to the outside of the exterior material for electricalstorage devices, the method comprising the step of interposing theadhesive film for metal terminal according to claim 1 between the metalterminal and the exterior material for electrical storage devices, andsealing the electrical storage device element with the exterior materialfor electrical storage devices.